One-pot preparation of cross-linked amphiphilic fluorescent polymer based on aggregation induced emission dyes

Facile one-pot preparation of cross-linked amphiphilic fluorescent polymer based on aggregation induced emission (AIE) dyes and 2-isocyanatoethyl methacrylate (IM) has been developed. This was carried out first by free radical polymerization between AIE monomer (PhE) and IM, and then polyethyleneimine (PEI) was introduced to obtain the cross-linked fluorescent polymer. The resulted cross-linked amphiphilic polymer was prone to self-assemble into stable nanoparticles in aqueous solution with surplus amino groups on the surface which made them highly water dispersible and can be further functionalized. The as-prepared fluorescent polymer nanoparticles (PhE-IM-PEI FPNs) were fully characterized by a series of techniques including ¹H NMR spectrum, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, dynamic light scattering, UV-vis absorption spectrum, and fluorescence spectra. Such FPNs demonstrated intense orange fluorescence with a high quantum yield of about 40%. Biocompatibility evaluation and cell uptake behavior of the nanoparticles were further investigated to explore their potential biomedical applications; the demonstrated excellent biocompatibility made them promising for cell imaging.